162 



Drainage hy Steam Power. 



feet below the surface. Faggots and brushwood were also used 

 on the side next the embankment. The top of the whole of the 

 piling was covered with clay. 



Description of the Engine and Water-ioheel. — The engine is one 

 of Messrs. Benjamin Hick and Son's independent frame engines, 

 combining the high-pressure and condensing principle. The 

 steam is admitted at the commencement of the stroke at about 

 30 lbs. on the square inch, and afterwards reduced to such a 

 pressure before the termination of the stroke as to be easily con- 

 densed. This is effected by a peculiar arrangement of the steam- 

 valves, by which the steam is cut off at different portions of the 

 stroke according to the amount of work to be done : great saving 

 is effected by this arrangement. This engine is nominally of 

 20-horse power, but can be worked up to considerably more, 

 though it is not more than half loaded by its present ordinary 

 work. The cylinder is 23 inches diameter, with a 3 feet 

 stroke. 



The scoop-wheel is 30 feet in diameter ; the floats or pallets 

 are 16 inches broad, working in a wheel-race of stone work 16J- 

 inches wide, and the extreme dip of the wheel is 4 feet 4 inches. 

 The float-boards are 4 feet 8 inches long, and are set as tangents 

 to a circle 9 feet diameter, as shown by the annexed drawing. 



The speed at which the wheel is worked, and which is ascertained 

 to be the best, is 4t revolutions per minute, or 400 feet at the 

 periphery of the wheel. Subjoined is a section of the wheel and 

 wheel-house. 



